The present invention relates to a scanner, and more specifically to an image pick-up module transmission arrangement for a scanner which enables the image pick-up module to be stably smoothly reciprocated in the scanning path to positively pick up the image of document up.
Scanners have been intensively used with computers in offices for text and graphic document data input. A regular scanner for this purpose is generally comprised of a transparent glass, an image pick-up module, a transmission mechanism, an electronic control circuit, a power supply unit, and a machine base. During the operation of a scanner, the light path must be maintained stable so that the image of document can be positively picked up by the image pick-up module. If the light path is not maintained stable, image distortion becomes inevitable. To a high resolution scanner of CIS (contact image sensor) type scanner, the requirement for a stable light path is critical.
FIG. 1 shows an image pick-up module transmission arrangement for a scanner according to the prior art. According to this arrangement, the image pick-up module is driven to move back and forth in the scanning path by a motor drive through a belt transmission mechanism. Because the belt transmission mechanism produces vibration when the motor drive is started, the reciprocating motion of the image pick-up module which is unstable may affect the scanning quality. Furthermore, because the belt transmission mechanism is mounted in the machine base, the outer shell of the scanner tends to be put out of shape due to change of ambient temperature and humility. When the outer shell of the scanner is deformed, the light path becomes unstable, in consequence the scanning quality is affected.